January 21, 2013

NASA's Mars Reconnaissance Orbiter is providing spectrometer data that shows a wet underground environment on Mars on the floor of McLaughlin Crater that adds to an increasingly complex picture of the Red Planet's early evolution. The Martian crater is 57 miles (92 kilometers) in diameter and 1.4 miles (2.2 kilometers) deep. McLaughlin's depth apparently once allowed underground water, which otherwise would have stayed hidden, to flow into the crater's interior. Layered, flat rocks at the bottom of the crater contain carbonate and clay minerals that form in the presence of water. McLaughlin lacks large inflow channels, and small channels originating within the crater wall end near a level that could have marked the surface of a lake. The crater sits at the low end of a regional slope several hundreds of miles, or kilometers, long on the western side of the Arabia Terra region of Mars. As on Earth, groundwater-fed lakes are expected to occur at low regional elevations. Therefore, this site would be a good candidate for such a process.

Together, these new observations suggest the formation of the carbonates and clay in a groundwater-fed lake within the closed basin of the crater. Some researchers propose the crater interior catching the water and the underground zone contributing the water could have been wet environments and potential habitats. The findings are published in Sunday's online edition of Nature Geoscience.

"Taken together, the observations in McLaughlin Crater provide the best evidence for carbonate forming within a lake environment instead of being washed into a crater from outside," said Joseph Michalski, lead author of the paper, which has five co-authors. Michalski also is affiliated with the Planetary Science Institute in Tucson, Ariz., and London's Natural History Museum. Michalski and his co-authors used the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on the Mars Reconnaissance Orbiter (MRO) to check for minerals such as carbonates, which are best preserved under non-acidic conditions.

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Launched in 2005, the Mars Reconnaissance Orbiter and its six instruments have provided more high-resolution data about the Red Planet than all other Mars orbiters combined. Data are made available for scientists worldwide to research, analyze and report their findings.

"A number of studies using CRISM data have shown rocks exhumed from the subsurface by meteor impact were altered early in Martian history, most likely by hydrothermal fluids," Michalski said. "These fluids trapped in the subsurface could have periodically breached the surface in deep basins such as McLaughlin Crater, possibly carrying clues to subsurface habitability."

"This new report and others are continuing to reveal a more complex Mars than previously appreciated, with at least some areas more likely to reveal signs of ancient life than others," said Mars Reconnaissance Orbiter Project Scientist Rich Zurek of NASA's Jet Propulsion Laboratory.

The Daily Galaxy via NASA

Image credit: This view of layered rocks on the floor of McLaughlin Crater shows sedimentary rocks that contain spectroscopic evidence for minerals formed through interaction with water. Image credit: NASA/JPL-Caltech/Univ. of Arizona

Comments

Where did all of Mars water go? Some underground, some changing into frozen CO2, most
evaporated, due to a lack of an atmosphere and was absorbed by Earth. Where did
earth's water come from, why Mars! Attracted by the Sun's and earth's gravity. What
cooled Earth enough for life to form, why the water from Mars. If Mars had had an
atmosphere, Earth would probably look like Mars today, dry and barren.